Consistent logging

Details

Description

Logging dependencies are very inconsistent. It seems we have absolute dependencies on log4j, yet use slf4j sometimes, and log4j other times. In some of our tests we have slf4j-nop as a test dependency.

It seems we could consolidate a lot of this if we simply did:

slf4j-api : compile

slf4j-log4j12 : runtime

slf4j-nop : test

log4j : runtime

We could do this in the parent POM and get rid of all the different dependencies throughout the code.

I don't know that we could ever use anything other than slf4j-log4j12 as the implementation (unless our dependencies broke away from using log4j directly also), but at least we'd clean up all the logging dependencies in our code/build, and would be ready to switch to something better if something came along. Further, if somebody wanted to reuse our code, and weren't tied to log4j, because they didn't need our transitive dependencies that locked in log4j, they could easily depend on their own slf4j implementation jar, and all the logging in our code would still work correctly for them without needing to use something like log4j-over-slf4j.